g-C₃N₄/TiO₂ Composite Film in the Fabrication of a Photocatalytic Air-Purifying Pavements

The fabrication of a photocatalytic air-purifying pavement with a facile loading route, long depolluting period, and excellent deNO_x activity under weak solar irradiation is essential for ambient air purification. Herein, a promising methodology is developed relying on the exploitation of a graphitic carbon nitride/TiO₂ (g-C₃N₄/TiO₂) composite hydrosol at room temperature. The TiO₂ hydrosol can act as a source of photocatalyst and dispersant for g-C₃N₄ during loading. The photoinduced hydrophilicity, adhesive force, and regeneration tests in the laboratory show the long-term deNO_x application potential of g-C₃N₄/TiO₂ coatings. Field studies indicate that the NO removal rate is 70.7% of g-C₃N₄/TiO₂-coated pavement in the morning (07:00–10:00) and afternoon (17:00–19:00), at which times solar radiation is weakest. The deNO_x efficiency is influenced by solar irradiation and traffic volume. The latter exerts a more significant influence on deNO_x efficiency than the former. A desirable route in fabricating a photocatalytic air-purifying pavement is provided and offers a promising photocatalyst suitable for outdoor environmental remediation.